This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-162601, filed Jun. 9, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a substrate processing apparatus, for example, for performing coating processing using a resist solution, developing processing, and the like for a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, or the like.
In photolithography in a semiconductor device fabricating process, a semiconductor wafer (hereinafter referred to as a wafer) is coated with a resist, the coated resist is subjected to exposure processing in accordance with a predetermined pattern and then developing processing, whereby the predetermined pattern of resist film is formed. Such a series of processing is performed by a system in which an aligner is connected to a coating and developing apparatus.
FIG. 12 is a plan view showing a conventional example of such an apparatus, and a substrate cassette C housing 25 substrates, for example, semiconductor wafers is carried into a cassette stage 1 of a cassette station A1. A processing station A2 is connected to the cassette station A1, and an aligner not illustrated is connected to the processing station A2 with an interface station A3 between them.
A wafer W in the cassette C on the cassette stage 1 is taken out by a delivery arm 11, then sent to a coating unit 13 via a delivery section of a shelf unit 12, and coated with a resist there. Thereafter, the wafer W is transferred by the route of a main arm 14xe2x86x92a delivery section of a shelf unit 15xe2x86x92the interface station A3xe2x86x92the aligner, and exposed.
The exposed wafer W is transferred to the processing station A2 by the reverse route, developed in a developing unit not illustrated but provided at the lower tier of the coating unit 13, and then transferred by the route of the main arm 14xe2x86x92the delivery section of the shelf unit 12xe2x86x92the cassette C. Incidentally, each shelf of the shelf units 12, 15, and 16 is structured as a heating section, a cooling section, the aforesaid delivery section of the wafer W, or the like. Before and after the coating of the resist and before and after the developing processing, in order to perform each of the above processing at a predetermined temperature, heating and processing and cooling processing are performed in the shelf units 12, 15, and 16 in this order.
The processing station A2 is divided into a processing area composed of the coating unit and the developing unit and a transfer area in which the main arm 14 is disposed. The processing area has a very precisely regulated atmosphere and air from which impurities are removed and which is regulated at predetermined temperature and humidity is sent out thereto. The transfer area has a coarsely regulated atmosphere and air from which impurities are removed is sent out thereto.
Since the thickness of a resist film depends on the temperature during coating of a resist, it is required to apply the resist while the temperature of a wafer is regulated very precisely in this situation in which thinning of the resist film is promoted. Therefore, the present inventor observed that the temperature of the wafer W is regulated very precisely by performing two-stage cooling by means of two cooling sections. In other words, a first cooling section for cooling the wafer W heated to a predetermined temperature to a temperature not more than a first temperature, so to speak, for cooling the wafer W briefly and a second cooling section for subsequently cooling the wafer W to a second temperature lower than the first temperature while performing precise temperature control.
In this case, since there is no installation space in the processing area in the aforesaid layout, the second cooling section is provided in the transfer area. In such a layout, the wafer W passes through the transfer area with the coarsely regulated atmosphere, whose temperature and humidity are not regulated, while being transferred from the second cooling section to the coating unit 13. Therefore, even in the temperature of the wafer is very precisely regulated in the second cooling section, the temperature changes during subsequent transfer, and the temperature at the time of resist coating eventually comes to differ from an intended temperature. As a result, there is a possibility that uniformity of film thickness deteriorates.
To prevent the above possibility, it was considered that the processing station A2 has a very precisely regulated atmosphere whose temperature and humidity are regulated, but there is a disadvantage in that such enlargement of an area in which atmosphere regulation is performed causes an increase in cost.
An object of the present invention is to provide a substrate processing apparatus capable of improving uniformity of processing by performing coating processing of a coating solution while the temperature of a substrate is very precisely regulated.
According to the present invention, there is provided a substrate processing apparatus comprising a heating unit configured to heat a substrate, a first cooling unit configured to cool the substrate heated by the heating unit to a temperature not more than a first temperature, a second cooling unit configured to cool the substrate cooled by the first cooling unit to a second temperature lower than the first temperature, a substrate processing unit configured to perform coating processing of a coating solution for the substrate cooled in the second cooling unit, and a substrate transfer unit configured to transfer the substrate between the first cooling unit, the second cooling unit, and the substrate processing unit, and wherein a processing station is divided into a processing block in which the temperature is controlled and a transfer block, the processing block including the substrate processing unit and the second cooling unit, and the transfer block including the substrate transfer unit, the heating unit and the first cooling unit.
The processing station may be coupled to a cassette station having a mounting unit on which a substrate cassette receiving a plurality of substrates is mounted and a delivery unit configured to deliver the substrate from/to the substrate cassette mounted on the mounting unit so that the substrate is transferred to the processing station by the delivery unit.
According to the aforesaid structure, since the substrate cooled to the second temperature by the second cooling unit is transferred to the substrate processing unit in a temperature-controlled atmosphere, the temperature of the substrate does not change during transfer. Consequently, coating processing using a coating solution can be performed with the temperature of the substrate being maintained with high precision, resulting in improvement in the uniformity of processing.
Further, a plurality of processing stations are connected to each other, and at least one of the processing stations may be structured so that a substrate transfer unit delivers the substrate from/to both of a substrate processing unit in its own processing station and another substrate processing unit in the adjacent processing station. In this case, the substrate delivered to one processing station is transferred to another substrate processing unit in the adjacent processing station if a substrate processing unit in the one processing station is occupied, thereby raising processing capacity and securing a high throughput.
In the aforesaid invention, a substrate processing unit and a second cooling unit exclusively used for the substrate processing unit may be provided, and the substrate processing unit and the second cooling unit may be disposed in the same atmosphere. Further, a dedicated transfer unit configured to transfer the substrate between the heating unit and the first cooling unit may be provided.
A substrate processing apparatus of the present invention can be applied to an apparatus for performing coating processing using a coating solution for a substrate. More specifically, at least one of the processing stations includes a substrate processing unit configured to perform coating processing using a resist solution for the substrate. An aligner is connected to a last processing station which is positioned at a last stage when counted from the cassette station and on a side opposite to the cassette station. A substrate processing unit in the last stage processing station performs developing processing for the substrate exposed by the aligner.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by unit of the instrumentalities and combinations particularly pointed out hereinafter.